1. Field of the Invention
The present invention relates to a vacuum cleaner, and more particularly, to a multi-cyclone dust separating apparatus that can centrifugally separate impurities from the sucked air.
2. Description of the Related Art
In general, a vacuum cleaner includes a suction brush for sucking the air containing impurities from the bottom, a dust separating apparatus for separating the impurities from the air sucked through the suction brush, and a suction motor that generates a suction driving source. The dust separating apparatus normally uses a dust bag. The dust bag is frequently replaced and unsanitary. Accordingly, a multi-cyclone dust separating apparatus that can be semipermanently used without a dust bag has been recently widely used.
The cyclone dust separating apparatus is a dust separating apparatus that centrifugally separates impurities from the air by rotating the air containing the impurities. The cyclone dust separating apparatus includes a cyclone body (not shown), an air inflow hole formed on the side of the cyclone body, and a discharge guide tube (not shown) installed at the upper portion thereof. However, the air supplied to the cyclone body rotates and collides with the discharge air discharged through the discharge guide tube, thereby causing a pressure drop and a reduction in the suction force. Particularly, a multi-cyclone dust separating apparatus having a plurality of cyclones to improve the dust collecting efficiency has such problems in the secondary or tertiary cyclones composed of a plurality of small cyclones.
A multi-cyclone dust separating apparatus (having a primary cyclone and a plurality of secondary cyclones) filed by the present applicant (Korean Publication No. 10-2005-0025711) will now be briefly explained with reference to FIG. 1. Referring to FIG. 1, the multi-cyclone dust separating apparatus 10 includes a primary cyclone 30 for primarily centrifugally separating impurities from the sucked air, secondary cyclones 40 for secondarily centrifugally separating impurities from the air supplied from the primary cyclone 30, a dust collecting vessel 20 for collecting the impurities separated from the air in the primary and secondary cyclones 30 and 40, an inflow/outflow cover 50 for guiding the air discharged from the primary cyclone 30 to the secondary cyclones 40, and a cyclone cover 60 for externally discharging the air from the inflow/outflow cover 50 to the outer space of the dust separating apparatus.
The plurality of secondary cyclones 40 are disposed on the outer circumference of the primary cyclone 30 at predetermined intervals, for centrifugally separating minute dusts that have not been separated from the air in the primary cyclone 30. On the other hand, a grill member 34 is installed in the primary cyclone 30, for preventing the impurities from flowing backward and being discharged through an air outflow hole 33 of the primary cyclone 30. The inflow/outflow cover 50 includes inflow guide tubes 52 for guiding the air discharged from the primary cyclone 30 to the secondary cyclones 40, and discharge guide tubes 53 for externally discharging the air of the secondary cyclones 40. The predetermined portions of the discharge guide tubes 53 are inserted into the secondary cyclones 40. A suction motor (not shown) of a vacuum cleaner is directly or indirectly connected to a discharge port 61 of the cyclone cover 60.
The operation of the multi-cyclone dust separating apparatus 10 will now be described. When power is applied to the vacuum cleaner and the suction motor (not shown) is driven, the outside air is supplied to the primary cyclone 30 through the suction port 37, and the impurities in the outside air are primarily centrifugally separated and collected in the dust collecting vessel 20. The air separated from the impurities passes through the grill member 34, is distributed along the inflow guide tubes 52 of the inflow/outflow cover 50, and supplied to the plurality of secondary cyclones 20. The impurities of the air are secondarily centrifugally separated and collected in the dust collecting vessel 20. The air separated from the impurities is ascended, collected in the cyclone cover 60 through the discharge guide tubes 53, and externally discharged from the multi-cyclone dust separating apparatus 10 through the discharge port 61.
The multi-cyclone dust separating apparatus 10 has high dust collecting efficiency because the plurality of secondary cyclones 40 are disposed on the outer circumference of the primary cyclone 30, for sequentially centrifugally separating the impurities of the air.
However, the multi-cyclone dust separating apparatus 10 has the following problems.
First, when the air discharged from the primary cyclone 30 is supplied to the secondary cyclones 40 through the inflow guide tubes 52, as indicated by arrows A, most of the air is not supplied to the lower portions of the secondary cyclones 40 but directly discharged to the discharge guide tubes 53 by the suction force of the discharge guide tubes 53. Therefore, the minute impurities that have not been filtered in the primary cyclone 30 are externally discharged through the cyclone cover 60 with the air, thereby reducing the dust collecting efficiency of the multi-cyclone dust separating apparatus 10.
In order to solve the foregoing problem, the discharge guide tubes 53 can be inserted deeper into the secondary cyclones 40. However, the air supplied to the secondary cyclones 40 seriously collides with the discharge guide tubes 53 to cause the pressure drop and reduce the suction force. If the suction force decreases, the secondary cyclones 40 cannot form a proper rotary current, thereby reducing the dust collecting efficiency.
Second, the air centrifugally separated from the impurities in the primary cyclone 30 is ascended through the grill member 34 and supplied to the secondary cyclones 40 through the air outflow hole 33. Here, the air supplied from the four directions is mixed and eddied inside the grill member 34, to generate an eddy current. As a result, the pressure drop is generated in the air, and the suction force of the suction motor is reduced due to the air pressure drop.